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A single cylinder motorcycle seems to be the just about the simplest thing in world.

I mean, look at it.

One piston and cylinder. A couple of valves. One spark plug. One carb or one throttle body and one singular pipe.

My Briggs and Stratton lawn mower engine is fundamentally the same thing.

How the hell hard could it possibly be to get and keep this maddenly simple mechanism running at its best?

***

Apparently, pretty hard.

Look, when one spends $900 to acquire a 2002 model year motorcycle, and that motorcycle has less than 1800 miles on it, it’s not a surprise that one will be spinning some wrenches.

But for the simplest thing in the world, keeping The Blast on its game has proved to be a moving target, an endlessly shifting game of ‘what’s-not-right-now’?

When it was time for Finn to come home from the University of Maryland for the summer, I headed down there to bring the bike back home while Finn transported a car full of architectural models and computer gear. He’d mentioned that the bike had been stumbling off of idle, and he could ‘smell something oily’ on shut down.

For some reason, my unconscious mind instantly formed a clear mental picture of some form of big hairy exhaust leak.

I got down on one knee in front of the Buell, and pulled my cel phone from the pocket of my cargos. I flipped the flashlight app on — which just turns on the phone’s LED flash unit — and looked onto the cylinder head’s exhaust port.

Clear as day, I could see a pretty substantial crack that ran almost halfway around the circumference of the headpipe. At the worst part of the fracture, a bit of pipe about half the size of my pinky fingernail was missing in action.

After starting the bike, I stood about two feet in front of it with my hand held in front of me, and could feel the exhaust pulses as clearly as if I was standing by the exhaust exit.

After getting the bike back to the shop, I figured I’d pull the entire exhaust system, take a good hard look at it to see if it was serviceable, and then make the fix or replace call.

***

I’ll state for the record that Buell’s design choice to place their exhaust systems under the engine makes perfect sense from a mass distribution and roll moment perspective.

Where it doesn’t make sense is if you’re the poor suffering bastard that has to work on one of them if you don’t own a motorcycle service lift.

If Finn — who is starting to demonstrate a genuine aptitude for the use of oblique strategies in problem solving — hadn’t seen a different route to access a bolt his now vision challenged Old Man could not see, I might be lying out there in the driveway still.

With his help, though, we finally got the entire system free from its three mount points — the exhaust port, a mount on the front of the engine, and a bar that ran across the bottom rear of the frame.

It didn’t take much inspection to conclude that my initial notion of a trip to my favorite welders was really ill-advised.

Can you say….Big Hairy Exhaust Leak

Apart from the obvious damage to the exhaust exit– which was going to be somewhat challenging to repair because of the method Harley Davison engines use to secure the headpipe — one doesn’t have much room at all to increase the effective diameter of the headpipe with a weld because of the manner in which the retaining snapring/retaining flange have to slip over it.

The rest of the exhaust – which was a typical Buell design with three separate chambers and resonating tubes contained in the muffler — didn’t look that great either. There were at least two more places where welds were visibly deteriorating right before my eyes, and the likelihood that we were going to have to be making more such repairs six months hence was unacceptably high.

That, and the thing weighted a freaking ton.

For a very little motorcycle what appeared to be a 20 pound plus exhaust didn’t make a lot of sense to me.

In the Fix or Replace Department, this was coming down a firm Replace.

***

So I spent some time trying to figure out who made the best aftermarket system for The Blast. There really weren’t a lot of choices. And maybe even less choices than that if one remembers that Finn’s motorcycle spent a lot of time in an indoor parking garage with a lot of expensive automobiles with sensitive alarm systems.

Every time I’d ever ridden The Blast up to the top floor of the parking structure, I’d gassed the little bike hard on every ramp that led up to the next floor. With the stock exhaust in a confined space, the bike sounded pretty thumpy.

Thinking about what the bike would sound like in there with a stupid loud exhaust — I’m talking to you D&D Drag Pipe — all I could see was three dozen Lexus, Jaguars and Acuras with their alarms all bleating plaintively in unison.

Such a scenario would not end well.

Anyway.

The only manufacturers that still manufacture an aftermarket exhaust for this motorcycle are Vance & Hines and Jardine.

The Vance and Hines is a ‘closed course competition’ only pipe. Aluminum headpipe and muffler. When I called the Nice Folks at V&H, they told me their system was ‘pretty loud’. When I asked them about the availability of a baffle that might make the system quasi-socially-responsible, they referred me to a third party that they thought made one “that might work.”

Call me judgemental, but this wasn’t feeling like a solution.

Which brings us to the Jardine.

The Jardine system has a pretty similar aluminum muffler body. They do, however, sell a mated low decibel exhaust exit insert for it, and their headpipe is made of stainless steel.

In a two horse race, we had an obvious winner.

In looking to buy one, I was surprised to discover that Summit Racing — from whom I was accustomed to ordering parts for my now sadly-departed 95 Dodge pickup — also carried a rather astounding range of motorcycle hard parts — brake pads, rotors…exhausts.

Where the online price for the Jardine ranged between $409 and $489, Summit had it for $365. They didn’t stock it…. after I placed my order they would order one and have it drop-shipped from Jardine straight to me. They’d never have anything to do with the deal other than deposit their margin.

I ordered up the Jardine exhaust system from Summit Racing.

***

The exhaust and carburation on a stock Buell Blast are not optimized for performance.

The intake and exhaust are tuned and restrictive. The engine — if one could call that ‘tuned’ at all — is tuned for tractability and low levels of power and noise.

Ditching the stock exhaust would absolutely require completely overhauling the carb — new pilot and main jets, and maybe a few other things besides.

There are two unvarnished good things about Buell Blast ownership. The First Thing is the Buell Riders Online Blast Forum, which knows all — sees all. One member of the forum, Dan, even got off the couch and designed and manufactured components that addressed some of the bike’s design peculiarities.

The Second Thing is that the Blast shares its carburetor — a Keihin CV40 — with gazillions of Harley Davidson Sportsters, and a couple of sub-zillion HD Big Twins as well. What this means to you is that tuning parts, including hot rodding parts, are available both directly from HD and from a cadre of aftermarket companies as well.

There’s even a company — CV Performance, Inc — that only makes tuning parts for the HD CV40 carb.

Woo-hoo.

The Blast Online brothers have tables which provide the tested jet sizes for each aftermarket exhaust that has ever been made for the bike. CV Performance had those jets as stock items. They also had two little gems that also needed to be installed to civilize living with the bike.

The first was a hand adjustment wheel to replace the stock idle adjuster, which requires a screwdriver. Every Japanese motorcycle I’ve ever seen has one of these — HDs and their ilk, at least from the factory, apparently do not. The second was a similar hand wheel to replace that factory air mixture screw, which was factory sealed under an aluminum plug. The combo would make dialing the carb in post-install childs play. Use the top thumbwheel to dial in the correct idle speed. Then use the bottom thumbwheel to dial in the air mixture so that bike took throttle evenly off idle.

Bada bing, bada boom. Done.

I ordered up the entire batch of CV40 parts, then headed to my local hardware store to pick up some #4 washers.

Then there was nothing to do but wait for the postman.

***

Unlike Godot, the Postman actually showed up.

The exhaust system hit the shop first. The Jardine pipe looked the business — all the aluminum machining on the muffler, exhaust exit and low noise insert core looked like it was MotoGP-ready. The hardware they had used was also top-notch — aircraft grade nylock insert nuts, and an aviation grade clamp for the headpipe to silencer joint.

After work that day, Finn and I headed out to the driveway and spent a few minutes mounting the system. Other than working with the monster snap-ring that Harley uses to retain every headpipe they’ve ever made — which requires its own dedicated monster snap-ring pliers, naturally — the work proceeded smoothly and without incident.

Well, without incident if one is willing to discount having to mount the snapring twice after I realized that the retaining plate needed to be passed over the headpipe first before mounting the snapring. We got better the second time after the ‘practice run’.

Finn’s ability to visualize how things fit together definitely indicates he made the correct choice of careers. It also makes him the ideal mechanic’s assistant. He was once again able to identify a route to apply torque to a fastener under the bike that might have taken me somewhat longer. It also doesn’t hurt that he can see small print on components that seem to be decreasing in size, at least from my perspective.

Once the pipe was successfully mounted, Finn’s first impulse was to start the bike up.

“Naah, let’s wait on that, Finn. Based on the jet numbers we’ve had to order the stock jets should be waaay too small. Would run like crap if it runs at all. Patience, Grasshopper. The carb parts should be here tomorrow. This carb is dog-simple — the work will not take us very long.”

***

As expected, Friday’s mail had the package from CV performance.

Saturday a.m. we put the Blast up on the swingarm stand and set about liberating the carb.

We pulled the tank cover and fuel tank, removed the air filter, and were looking at the business end of the fuel system.

One of the required ‘adjustments’ was to raise the slide needle in its holder, in order to ensure that the off idle mixture didn’t lean out, causing stumbles or backfires. The carburetors to which I am accustomed have a snapring to retain them and multiple grooves in the needle to permit said adjustment.

Not so The Blast. Its needle has no provision for adjustment — it simply sits in the bottom of the slide where it is trapped in place by the slide return spring’s plastic retainer.

Which brings us back to the aforementioned #4 washers.

The #4 washers are just large enough to fit on the carb’s needle. They’re a known thickness. Determine how high you want to raise the needle, and do the math.

Given how the carb sits when installed in the motorcycle, the easiest place to do that procedure was right where it already was.

The diaphragm cover on the CV40 is held in place by four screws. One of those four screws also holds the throttle cable pulley. I pulled that corner first, and disconnected the throttle open and close cables from the carb.

After unscrewing the other three corners, the carb’s top, diaphragm and slide assemblies were in my hand.

All things considered — 14 years of limited use and benign neglect followed by one year of really intensive use — things looked surprisingly clean and generally pretty good. No serious gook or deposits, no visible wear. The diaphragm even checked out.

I pulled the carb’s needle out of the slide, slipped my washers underneath, and put the whole thing back together. I used some carb and choke cleaner to get the slide shining, seated the diaphragm in its groove on top of the carb body and buttoned the whole thing back up.

Next, we’d need to pull the carb out of the bike to do the jet service.

In The Blast, the carb is held in place by a single screw clamp on the cylinder head end, and three allen head bolts that connect it to an intake venturi fitting and the airbox. It’s about 10 minutes from intention to workbench.

Stupid Plug, Gooped Up Flange

What needed to be done was very straightforward.

Larger pilot jet and main jet needed to be installed. After bathing everything — carb body, float bowl — in carb cleaner and shining things up with clean shoprags, I replaced the entire main jet, needle jet holder/emulsion tube and needle jet stack with new parts.

A few artful turns of my favorite carb screwdriver, we had a new pilot jet, too.

We, collectively, are perilously close to a point in time where using the phrase ‘favorite carb screwdriver’ will not communicate any meaning whatsoever.

I noted how many threads of the idle speed screw were showing, then removed the screw. I installed my new idle speed thumbscrew adjuster and turned it by hand until the same number of threads were showing. That setting would be a good starting point.

The mixture screw install was a little more chewy.

The Nice Folks At The Factory had decided that the mixture screw was something which You Would Never Need and Should Not Be Allowed To Touch.

Funny, that.

Accordingly, they had thoughtfully press fit a nice aluminum plug in the mixture screw bore.

And that, brothers and sisters, is why God and Bosch made lithium ion powered rechargeable drills.

I draped the entire carburetor in clean shop towels, then fitted my smallest dentist-wannabe drill bit into the chuck.

After a deep breath to steady myself — wouldn’t want to mess this hole up — I slowly spun up the drill until I was sure my hole was in the center of the bore plug. 20 seconds of spin later, the bit punched through.

I threaded a self tapping sheet metal screw into my tiny hole, and then pulled the screw and plug out with a pliers. After clearing the drill swarf, I was able to remove the mixture screw and replace it with the EZ-Just Mixture Screw. I ran the EZ-Just down until it bottomed, then backed it out the 2 3/4 turns I’d been told was the approximate setting.

With everything in place, I replaced the float bowl on the CV40 using some Allen bolts also supplied by CV Performance — the original screws were Japan Industrial Standard (JIS) — which looks a lot like a Phillips head screw but really isn’t. In practical use, JIS screws get destroyed through the use of Phillips screwdrivers, since darn near no-one even knows what a JIS Screwdriver is, much less actually owns one.

I spent a little bit of time cleaning up the exterior of the carb body. It might be another 15 years before it got cleaned again, so I wanted to be thorough. I spent a little extra time giving the hairy eyeball and extra attention to the output side of the carb, where it fitted in to the rubber intake manifold.

These motorcycles are notorious for funky tuning resulting from intake leaks at that very spot. And to my eye it appeared that someone had tried to use some form of caulk or sealant to smooth over the cast-in groove in the carb’s exit flange. This little improvisation, it should be noted, would make the carb to rubber manifold joint far more likely to leak than if the groove was there for the rubber to conform to.

I cleaned it all out and returned the exterior of the carb body to stock finish and condition.

It was time to see what we had here.

***

3 Allen Bolts, 2 screwclamps and 3 10mm bolts later, the Blast was back together on the workstand.

I turned on the fuel petcock, and waited a suitable amount of time.

I may have actually twiddled.

I walked over to the other side of the bike, looking for errant fuel. I didn’t see, smell or slip and fall over in any.

I walked back to the left side of the bike and turned the key. The Blast went through its little electromechanical dance – whizzzz! – as it energized and started up the instrument displays.

I hit the starter — “whoooof… whoooof….whoooof…whoooof…”

There were a lot of places in that carburetor that didn’t yet have fuel where fuel was supposed to be.

“Whoooof… whoooof….whoooof…WHUMP! WHUMP…. wumpwumpwumpwumpwump….”

It was immediately apparent that the Blast had undergone a personality transplant. It wasn’t like it had taken a trip to full-on racetrack honk, but there was no longer any question you were listening to A Motorcycle.

Amazingly, the initial idle speed and mixture settings appeared to be pretty close. As the bike came down off the enriched high idle, idle speed was in the ballpark — I used the adjuster to goose it upward ever so slightly. Throttle response wasn’t bad either — I opened up the mixture screw until response started to soften, then went back a 1/4 turn.

Spot on and a rock solid thumping idle. Rolling the throttle open snapped rpms upward with a healthy bark from the new muffler.

I went inside to get a helmet and some gear.

***

Trolling out of the neighborhood it was clear that everything had changed.

Small changes in the throttle now produced noticeable and proportional results. One of the reasons I appreciate carbureted vehicles is that they exhibit analog response — the systems perform and provide feedback that is sensitive to the operational gestures of the driver or rider. Whacking the grip to immediately deliver LTO feels very different from smoothly rolling the throttle progressively to the stops. A throttle opening I select on a corner entry is exactly the throttle opening I get — not a slightly different one selected by some ride by wire software.

The Blast was now all kinds of responsive at low engine speeds and small throttle openings — something it absolutely was not before.

I mean, you could solidly short shift the bike and there’d be power in the next gear.

When I got to The Pike, I gassed it. After a short shift to second, I rolled the throttle open and wound second, and then third gear all the way out.

The sound of the engine was simply marvelous — a basso profundo machine gun, with a genuine snarl on the overrun when the throttle was snapped closed between shifts.

There was no popping or burbling on deceleration… running the engine up to high RPMs demonstrated a genuine power step and well more power and acceleration than had been there before. It seemed the rejetting work had been spot on — I’ll admit being surprised at the amount of new lunge coming out of a single two valve, aircooled, pushrod Sportster refugee cylinder.

I was down to the bottom of hill at the Brookside Inn bang-bang corners far sooner than I remember Blasting there previously.

I wound the gas on and charged the short straight and the steep right that lead back up the hill. The Brookside Parking Lot’s Ultra Glide clan’s gazes were definitely drawn by the sporting report from their Big Twins’ little brother.

Two thirds of the way up the long and steep grade I deliberately gave the gear up early, and let the bike pull fourth gear from well below the engine’s torque peak. With the thump of each power pulse coming back off the rock cut, I got another demonstration of the appeal of American power — big cylinders, comparatively low RPM, and unrestrictive exhausts making power and that booming wonderful sound.

I needed to get this bike back in Finn’s hands.

***

After I got back to the shop and got my gear off, Finn was geared up and ready.

With two “Brraps” he was around the corner and gone. As he left the neighborhood I could hear The Blast’s engine revving out as it headed up the highway.

I suspected I might not see Finn for a while.

***

And as I suspected, I didn’t. An hour, an hour and a half, maybe a little more — which is as much as you have gas for with the small Buell tank — before I heard the thumping coming back up the street, up the driveway and back into the shop.

Finn revved the engine twice before shutting it down.

Previously, Finn never revved the engine.

Now, it seems, you just got to. You can’t help yourself.

***

I’ve had the bike out several times since then, and each time is a revelation. I take it whenever I have a short trip to make that keeps me off the highways. On the backroads one just wants to revel in the sound — running the revs up and then engine braking to slow down — going “VOOObaaaaa… VOOObaaaaaa” and feeling the thrum of the motor through the footpegs and bars.

The bike is silly light and agile, and I’ve finally internalized its “You-Don’ts-Gots-To-Speed-Up-Coming-Out-Of-Corners-If-In-The-First-Place-You-Never-Slow-Down” Ethos. It seems The Blast’s throttle is perpetually opening – using it to set entries — torquing up on the way out.

The look of the Jardine system really cleaned up the appearance of the bike — the stainless steel headpipe also turned a nice bronze tone after it had been run and revved for a few miles. Finn and I both noticed that the weight reduction made the bike easier to turn in on corner entry. 15 pound weight loss on a 390 pound motorcycle is definitely noticeable.

Nice Tone, Nice Headpipe Color

I never want to get too cocky, but it feels like we’ve got this little motorcycle sorted out. It behaves like a real motorcycle and really is fun to ride in its chosen element.

I’ve got a better feeling about this bike getting him through another school year without requiring the laying on of hands (and wrenches).

There will aways be little projects, like fabbing up soft saddlebag guards out of 1/2″ electrical conduit after noticing that small hole abraded though the plastic drive belt pulley shroud. It amazing what you can do with the bike’s designed-in underseat bungee anchors, some threaded rod, some nuts and bolts, and a really large sledgehammer.

Then there’s the small matter of the AutoChoke. I am like Ahab in that I will carry the fight against the White Snowmobile Part until the end of my days. I’d had the Hoca Manual Choke Kit and Sportster Enrichener Valve installed, but the cable I’d procured didn’t have long enough a throw to close the enrichener 100% of the way.

8mm choke…meet 7mm choke…I’d have to buy a Sportster enrichener valve for this to work….

I’d sourced and modified a nice handlebar mounted control — the whole thing looked factory, but the enrichener slide was only closing about 90% and I ended up having to reinstall the AutoChoke. I’ve subsequently obtained a cable that looks like it will work but with summer nearly over I may just be out of time.

The Clamp (Modified)

Looks Factory

This isn’t over yet, Moby Dick.

We’ll get a ride or two together in the coming weeks, but then Finn and his motorcycle will head back to University.

With both Finn and The Blast gone, it really will be quiet around here in Jefferson.